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Highlights • Reconciliation of ozone microwave data in the HIRAN and JPL databases. • Explanation of theory for centrifugal distortion of permanent dipole. • Far-infrared absolute intensity measurement. • Impact of intensity adjustment for ozone remote sensing. Abstract This note provides a citable reference to a database reconciliation effort for ozone pure rotational intensities. The permanent dipole moment and theoretical adjustments for centrifugal distortion are utilized in a predictive calculation that is compared to experimental measurements. This prediction has been available in the JPL spectral line catalog since 2005, but has been at odds with the HITRAN database, which was originally based on an atlas provided by Flaud (HITRAN 1992) and subsequently scaled by 4% (HITRAN 2004). Using a modified partition function and isotopic abundance factor, the JPL 2005 prediction has now been utilized to create a self-consistent entry as an interim update to the HITRAN2016 database. Ramifications of the intensity change for users of HITRAN versions 2004–2012 are discussed. New pure rotational intensity measurements were carried out supporting the validity of the JPL 2005 database. [ABSTRACT FROM AUTHOR]

This manuscript reports an effort to improve the absolute accuracy of ozone intensities in the 10 µm region via a transfer of the precision of the rotational dipole moment onto the infrared measurement. The approach determines the ozone mixing ratio through alternately measuring seven pure rotation ozone lines from 692 to 779 GHz. A multispectrum fitting technique was employed. The results determine the column with absolute accuracy of 1.5% and the intensities of infrared transitions measured at this accuracy reproduce the recommended values to within a standard deviation of 2.8%. [ABSTRACT FROM AUTHOR]

• The first study of the effect of temperature on the speed-dependence effect for oxygen fine-structure lines. • Significantly different temperature behavior of pressure broadening γ 0 and its speed-dependence γ 2 for different N. • Change of the sign of temperature exponent of γ 2. • Accurate parameters of the line center pressure shifting. The microwave spectrum of oxygen, which consists of the fine-structure lines, is a tool for atmospheric research. An accurate line shape profile is necessary for modeling of the atmospheric absorption and interpreting the radiometric data. In this study, more than 500 recordings of the oxygen millimeter wave lines were obtained in a wide range of pressures (0.3–1500 Torr) and temperatures (235–357 K) using two experimental techniques that differ in principle of operation. High quality of the experimental spectra and negligible baseline allowed accurate analysis of the line shape using the quadratic speed-dependent Voigt profile. Line shape parameters for six fine-structure oxygen lines (N = 1+,1−, 7+, 11+, 15+, and 19−), including self-broadening and self-shifting, were refined. The parameters of the speed dependence of the collision relaxation rate demonstrated significantly different temperature behavior for different rotational states. In particular, the ratio γ 2 /γ 0 reveals temperature independence for the lowest rotational state; the dependence becomes notable with the growth of rotational excitation. For practical use, the empirical functions were fitted to the experimental temperature and rotational dependences of the line shape parameters. [ABSTRACT FROM AUTHOR]

Retrievals of atmospheric composition from near-infrared measurements require measurements of airmass to better than the desired precision of the composition. The oxygen bands are obvious choices to quantify airmass since the mixing ratio of oxygen is fixed over the full range of atmospheric conditions. The OCO-2 mission is currently retrieving carbon dioxide concentration using the oxygen A-band for airmass normalization. The 0.25% accuracy desired for the carbon dioxide concentration has pushed the required state-of-the-art for oxygen spectroscopy. To measure O 2 A-band cross-sections with such accuracy through the full range of atmospheric pressure requires a sophisticated line-shape model (Rautian or Speed-Dependent Voigt) with line mixing (LM) and collision induced absorption (CIA). Models of each of these phenomena exist, however, this work presents an integrated self-consistent model developed to ensure the best accuracy. It is also important to consider multiple sources of spectroscopic data for such a study in order to improve the dynamic range of the model and to minimize effects of instrumentation and associated systematic errors. The techniques of Fourier Transform Spectroscopy (FTS) and Cavity Ring-Down Spectroscopy (CRDS) allow complimentary information for such an analysis. We utilize multispectrum fitting software to generate a comprehensive new database with improved accuracy based on these datasets. The extensive information will be made available as a multi-dimensional cross-section (ABSCO) table and the parameterization will be offered for inclusion in the HITRANonline database. [ABSTRACT FROM AUTHOR]

The IR spectra of water vapor–carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm −1 in order to explore the effect of colliding CO 2 and H 2 O molecules on their continuum absorptions. The sample temperatures were 294, 311, 325 and 339 K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm −1 , the continuum absorption coefficient C H 2 O + C O 2 is about 20 times stronger than the water–nitrogen continuum absorption coefficient C H 2 O + N 2 . On the other hand, in the far wing region (2500 cm −1 ) of the ν 3 CO 2 fundamental band, the binary absorption coefficient C C O 2 + H 2 O appears to be about one order of magnitude stronger than the absorption coefficient C C O 2 + C O 2 in pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the addition of Collision-Induced Absorption (CIA) into the HITRAN compilation. The data from different experimental and theoretical sources have been cast into a consistent format and formalism. The implementation of these new spectral data into the HITRAN database is invaluable for modeling and interpreting spectra of telluric and other planetary atmospheres as well as stellar atmospheres. In this implementation for HITRAN, CIAs of N2, H2, O2, CO2, and CH4 due to various collisionally interacting atoms or molecules are presented. Some CIA spectra are given over an extended range of frequencies, including several H2 overtone bands that are dipole-forbidden in the non-interacting molecules. Temperatures from tens to thousands of Kelvin are considered, as required, for example, in astrophysical analyses of objects, including cool white dwarfs, brown dwarfs, M dwarfs, cool main sequence stars, solar and extra-solar planets, and the formation of so-called first stars. [Copyright &y& Elsevier]

Abstract: High-resolution water vapor absorption spectra have been measured at room temperature in the 8800–11,600cm−1 spectral region. They were obtained using the mobile BRUKER IFS 120M Fourier transform spectrometer (FTS) from ULB-SCQP coupled to the 50m base long multiple reflection White type cell in GSMA laboratory. The absorption path was 600m and different H2O/HDO/D2O mixtures were used. Measurements of line positions, intensities and self-broadening coefficients were performed for the HD16O isotopologue. 6464 rovibrational assignment of the observed lines was made on the basis of global variational predictions and allowed the identification of new energy levels. 3ν 3, 2ν 1+ν 3, 3ν 1+ν 2, ν 1+2ν 3 and 2ν 2+2ν 3 are the five strongest bands. The present paper provides a complementary data set on water vapor for atmospheric and astrophysical applications. [Copyright &y& Elsevier]

Abstract: The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10−6 to 35,877.031cm−1. The successful performances of the new generation of hyperspectral sounders depend ultimately on the accuracy to which the spectroscopic parameters of the optically active atmospheric gases are known, since they constitute an essential input to the forward radiative transfer models that are used to interpret their observations. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer; http://smsc.cnes.fr/IASI/index.htm) on board the METOP European satellite through the GEISA/IASI database derived from GEISA. Since the Metop-A (http://www.eumetsat.int) launch (19 October 2006), GEISA is the reference spectroscopic database for the validation of the level-1 IASI data. Also, GEISA is involved in planetary research, i.e., modeling of Titan''s atmosphere, in the comparison with observations performed by Voyager, or by ground-based telescopes, and by the instruments on board the Cassini–Huygens mission. GEISA, continuously developed and maintained at LMD (Laboratoire de Météorologie Dynamique, France) since 1976, is implemented on the IPSL/CNRS (France) “Ether” Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are registered for on line use of GEISA. [Copyright &y& Elsevier]

Abstract: We report on the consistency of water vapour line intensities in selected spectral regions between 800–12,000cm−1 under atmospheric conditions using sun-pointing Fourier transform infrared spectroscopy. Measurements were made across a number of days at both a low and high altitude field site, sampling a relatively moist and relatively dry atmosphere. Our data suggests that across most of the 800–12,000cm−1 spectral region water vapour line intensities in recent spectral line databases are generally consistent with what was observed. However, we find that HITRAN-2008 water vapour line intensities are systematically lower by up to 20% in the 8000–9200cm−1 spectral interval relative to other spectral regions. This discrepancy is essentially removed when two new linelists (UCL08, a compilation of linelists and ab-initio calculations, and one based on recent laboratory measurements by Oudot et al. (2010) in the 8000–9200cm−1 spectral region) are used. This strongly suggests that the H2O line strengths in the HITRAN-2008 database are indeed underestimated in this spectral region and in need of revision. The calculated global-mean clear-sky absorption of solar radiation is increased by about 0.3Wm−2 when using either the UCL08 or Oudot line parameters in the 8000–9200cm−1 region, instead of HITRAN-2008. We also found that the effect of isotopic fractionation of HDO is evident in the 2500–2900cm−1 region in the observations. [Copyright &y& Elsevier]

Abstract: The absorption spectra of H2O+N2 mixtures, as well, as the spectra of pure gases, have been measured using a Fourier-transform infrared spectrometer at a resolution of 0.1cm−1. The sample temperatures were 326, 339, 352, and 363K. Water vapor pressures varied from 8 (60torr) to 34.5kPa (259torr). The nitrogen pressure was kept constant at about 414kPa (4.1atm). The path length was 100m. The continuum absorption coefficients obtained in the spectral range 2000–3250cm−1 (3.1–5μm) do not depend significantly on temperature, as is predicted by the well known MT_CKD model. But there are significant deviations in the continuum spectral behavior and magnitude. Around 2050cm−1 the measured absorption coefficients C f are about two times larger than those of the model. This deviation grows rapidly at shorter wave lengths, reaching a maximum of two orders of magnitude in the middle of the window at 2500cm−1. At this point, the deviation starts to decrease significantly and around 3100cm−1 our results are in agreement with the MT_CKD model. This behavior of the deviation is due to the broad and structureless feature in the region of the nitrogen fundamental band. Most likely, this feature is the N2 fundamental band component, induced by collisions between H2O and N2 molecules. The data obtained and a comparison with the results from the other available sources are presented. [Copyright &y& Elsevier]

Abstract: The pure water-vapor continuum absorption in the 2.88 to 5.18μm spectral region has been measured using a Fourier-transform infrared spectrometer at a resolution of 0.1cm−1. The sample temperatures and pressures varied from 311 to 363K and from 2.8kPa (21Torr) to 34.5kPa (259Torr), respectively. The path lengths used in the study ranged from 68 to 116m. Under these conditions, the continuum absorption in the middle of the 4μm window is quite detectable reaching as high as 4%. The spectral processing included calculations to fit and remove the H2O ro-vibrational structure. In the region around 5μm, the absorption coefficients obtained are in good agreement with those of the commonly used MT_CKD continuum model. However at shorter wavelengths, the observed values significantly deviate from the model. Inspection of the present data as well as that of previous measurements leads to the conclusion that the MT_CKD model despite the latest updates significantly underestimates the rate of the continuum temperature dependence over the 4μm atmospheric window. Line strengths for 189 H2O transitions were obtained from the spectral processing. The deviation of these measured intensities from those listed in the HITRAN database is randomly scattered around zero to within several percents and no systematic trends were detected. [Copyright &y& Elsevier]

Abstract: The improved database of HNO3 spectroscopic parameters in the 600–950cm−1 spectral region presented in [Gomez L, Tran H, Perrin A, Gamache RR, Laraia A, Orphal J, et al. Some improvements of the HNO3 spectroscopic parameters in the spectral region from 600 to 950cm−1. JQSRT 2008, in press] is tested by comparisons between calculations and atmospheric remotely sensed absorption and emission spectra. The line parameters in the 11.3μm region are validated using ground-based Fourier transform solar absorption measurements, whereas those in the 13.1μm region are successfully tested using balloon-borne atmospheric emission spectra. In both regions, the quality of the line parameters and the consistency between band intensities is confirmed through comparisons with emission spectra collected by the satellite-borne MIPAS instrument. [Copyright &y& Elsevier]

Abstract: The gas absorption process scheme in the broadband radiative transfer code “mstrn8”, which is used to calculate atmospheric radiative transfer efficiently in a general circulation model, is improved. Three major improvements are made. The first is an update of the database of line absorption parameters and the continuum absorption model. The second is a change to the definition of the selection rule for gas absorption used to choose which absorption bands to include. The last is an upgrade of the optimization method used to decrease the number of quadrature points used for numerical integration in the correlated k-distribution approach, thereby realizing higher computational efficiency without losing accuracy. The new radiation package termed “mstrnX” computes radiation fluxes and heating rates with errors less than 0.6W/m2 and 0.3K/day, respectively, through the troposphere and the lower stratosphere for any standard AFGL atmospheres. A serious cold bias problem of an atmospheric general circulation model using the ancestor code “mstrn8” is almost solved by the upgrade to “mstrnX”. [Copyright &y& Elsevier]

Abstract: About 200 pure water-vapor spectra covering the region from 800 to 3500cm−1 were recorded with resolution of 0.1cm−1 at temperatures 311, 318, 325, 339, 352, and 363K using a 2m base White cell coupled to the BOMEM DA3.002 FTIR spectrometer. The water-vapor pressure varied from 28 to 151mbar (21–113Torr). Under these conditions, the continuum absorbance is quite measurable with the available path lengths up to 116m. A program was developed for spectral processing that calculates, fits, and removes ro-vibrational structure from the spectrum. The spectra obtained were used to retrieve averaged and smoothed binary absorption coefficients over the region from 800 to 1250cm−1. Our continuum data extrapolated to room temperature are in reasonable agreement with the MT_CKD continuum model. But at higher temperatures the MT_CKD model provides very low values, which are up to 50% less than those experimentally measured. [Copyright &y& Elsevier]

Abstract: The development of Gestion et Etude des Informations Spectroscopiques Atmosphériques (GEISA: Management and Study of Spectroscopic Information) was started over three decades at Laboratoire de Météorologie Dynamique (LMD) in France. GEISA is a computer accessible spectroscopic database, designed to facilitate accurate forward radiative transfer calculations using a line-by-line and layer-by-layer approach. More than 350 users have been registered for on-line use of the GEISA facilities. The current 2003 edition of GEISA (GEISA-03) is a system comprising three independent sub-databases devoted respectively to: line transition parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer on board of the METOP European satellite) through the GEISA/IASI database derived from GEISA. The GEISA-03 content is presented, placing emphasis on molecular species of interest for Earth and planetary atmosphere studies, with details on the updated 2008 archive underway. A critical assessment on the needs, in terms of molecular parameters archive, related with recent satellite astrophysical missions is made. Detailed information on free on-line GEISA and GEISA/IASI access is given at http://ara.lmd.polytechnique.fr and http://ether.ipsl.jussieu.fr. [Copyright &y& Elsevier]

Abstract: Water vapor spectroscopy data for the 720nm absorption band ( polyad) are validated in the context of atmospheric radiative transfer calculations. We validate line parameters from the HITRAN-2000 database and from the ULB-UFR-BIRA database which have been used for the 2004 release of HITRAN. For this purpose, ground-based high resolution observations of the direct solar radiation are compared with simulated spectra. Line parameters are selected for validation based on a full error characterization including instrument noise and uncertainties in the atmospheric profile data. For a subset of the line parameters validated in the present study independent high-accuracy data are available. The comparison with these independent reference data confirms the capability of our approach to improve water vapor spectroscopic data. [Copyright &y& Elsevier]

Abstract: New high-resolution water vapor absorption spectra were obtained at room temperature in the 4200–6600cm−1 spectral region by combining Fourier transform spectrometers (FTS) with single and multiple reflection cells. With absorption paths from 0.3 to 1800 m in pure and air diluted water vapor, accurate measurements of about 10400 lines in an intensity range from 10−29 to 10−19 cm/molecule have been performed. Positions, intensities, self- and air-broadening coefficients and air-induced shifts were determined for the H2 16O, H2 17O, H2 18O and HDO isotopologues. The rovibrational assignment of the observed lines was performed with the use of global variational predictions and allowed the identification of several new energy levels. One major contribution of this work consists of the identification of 3280 new weak lines. A very close agreement between the new measured parameters and those listed in the database is reported as well as between the observations and the most recent variational calculations for the positions and the intensities. The present parameters provide an extended and homogeneous data set for water vapor, which is shown to significantly improve the databases for atmospheric applications, especially in the transmission windows on both sides of the band centered at 5400cm−1. [Copyright &y& Elsevier]

Abstract: The content of the current (2003) version, GEISA/IASI-03, of the computer-accessible spectroscopic database, GEISA/IASI, is described. This “system” or database is comprised of three independent spectroscopic archives, which are (a) a database of individual spectral line parameters on 14 molecules, , , , , CO, , , NO, , , , OCS, , , and the related 51 isotopomers and isotopologues, representing 702,550 entries, in the spectral range 599–, (b) a database of spectral absorption cross-sections(6,572,329 entries related to six molecules, CFC-11, CFC-12, CFC-14, HCFC-22, , ), and a catalogue of microphysical and optical properties (mainly, the refractive indices) of atmospheric aerosols. The modifications and improvements, which have been implemented since the earlier editions of this database, in terms of content and management, have been explained in detail. GEISA/IASI has been created with the specific purpose of assessing the capability of measurement by the IASI instrument within the designated goals of ISSWG in the frame of the CNES/EUMETSAT European Polar System preparation. All the archived data can be handled through a user-friendly associated management software, which is posted on the ARA/LMD group web site at http://ara.lmd.polytechnique.fr. [Copyright &y& Elsevier]

The near-IR (in the range 5000–10 000 cm−1, 1–2 μm) bands of water vapour have been measured in absorption in the laboratory at sub-Doppler spectral resolution (up to 0.0054 cm−1 after numerical apodisation) by Fourier transform spectroscopy. Measurements have been made at 296 K on pure water vapour (at pressures between 2 and 20 hPa) and mixtures of water and air (at total pressures of 100 and 1000 hPa), at optical path lengths in the range 0.26–9.75 m. Measured absorption intensities have been compared with values calculated using the HITRAN 2000 molecular database. These comparisons indicate that the intensities of the 2ν(1.4 μm) and 2ν+δ(1.14 μm) bands are underestimated in HITRAN 2000 by approximately 15% and 20%, respectively, for pure water vapour measurements, and 12% for both bands in the case of water–air mixtures. The ν+δ (1.86 μm) band is in good agreement (0.4% for pure water vapour and less than 6% for mixtures with air) with HITRAN 2000. For typical atmospheric conditions, these absorption bands are sufficiently strong that radiation is fully absorbed at wavelengths in the region of the band centres. Hence the extra absorption that has been identified has only a modest impact (0.16 W m−2 or about 0.2%) on the global-mean clear-sky absorption of solar radiation. The impact in the upper troposphere is several times larger. [Copyright &y& Elsevier]

Line parameters of water vapor have been obtained in the 13 000–9250 cm−1 spectral region. The measurements were performed with a high resolution Fourier transform spectrometer coupled to long-path multiple reflection cells. Emphasis was put on the determination of accurate parameters for the weak lines, most of which have not been previously reported in the literature. A total of 7061 lines have been studied. Their positions and intensities have been determined, and for many of analyzed lines, self- and air-broadening coefficients, as well as pressure-induced shifts were obtained. A preliminary analysis of the dependence of the broadenings and shifts, with vibrational and rotational quantum numbers is given. The discussion is focused on the comparison between our measured parameters and those listed in the HITRAN database. A very good agreement is reported for the positions and intensities. It is suggested that the construction of a comprehensive and complete dataset for water vapor in this spectral region requires the merging of independent measurements, and of calculated values of broadenings and shifts for weak and blended lines. [Copyright &y& Elsevier]